(386723) 2009 YE7
A classical KBO and Haumea-family member with water ice.
(386723) 2009 YE7 is a trans-Neptunian object first spotted by David Rabinowitz on December 17, 2009, using the La Silla Observatory in Chile. It belongs to the classical Kuiper belt, meaning its path around the Sun is not shaped by Neptune’s orbital resonance, much like 15760 Albion, though its orbit is far more elongated and tilted. One full lap around the Sun takes it just over 247 Earth years, with an average distance of roughly 44 AU. It came to perihelion around 1868, and to aphelion in 2015; currently it sits about 50.7 AU away, and it will swing back to perihelion near 2163. Astronomers have logged 70 observations of this object, including precovery images from 2006, and its orbital quality code stands at 4. To estimate its size, scientists need both its absolute magnitude (H) and its albedo—how much light it reflects. When first found, 2009 YE7 was thought to have an H of 2.8, which would have made it the brightest Kuiper belt object ever discovered from the Southern Hemisphere. However, its actual absolute magnitude is 4.5. Because this value is dimmer than H=1, the object will not be reviewed by two naming committees and will not automatically qualify as a dwarf planet under IAU rules. At H=4.5, it would be a strong dwarf planet candidate if its albedo were 0.09. The object is likely far smaller than initially believed, and if it is a highly reflective icy member of the Haumea family—as suggested by its Haumea-like orbit and detected water ice—its albedo could reach 0.7, yielding a diameter near 200 kilometers (120 miles). Its true albedo remains unknown; a lower value would mean a larger size.
Quick Facts
- Minorplanet
- yes
- Background
- #C2E0FF
- Discoverer
- David Rabinowitz
- Discovered
- 17 December 2009
- Mpc Name
- (386723) 2009 YE · 7
- Mp Category
- TNO / Cubewano / Haumea family
- Epoch
- 13 January 2016 (JD 2457400.5)
- Aphelion
- 50.694 AU
- Perihelion
- 37.893 AU
- Time Periastron
- ≈ 5 May 2164 / ±15 days
- Semimajor
- 44.293 AU
- Eccentricity
- 0.14450
Facts from the source article.
Lore & Background
2009 YE7 was discovered by David Rabinowitz on December 17, 2009, at the La Silla Observatory in Chile. It is a classical Kuiper belt object, meaning its orbit is not controlled by an orbital resonance with Neptune, similar to 15760 Albion but with a much greater orbital eccentricity and inclination. It completes one orbit around the Sun in just over 247 Earth years at an average distance of about 44 AU. It came to perihelion around 1868, and to aphelion in 2015; it is currently about 50.7 AU from the Sun and will return to perihelion around 2163. When first discovered, it was believed to have an absolute magnitude (H) of 2.8, which would have made it the first bright KBO found from the Southern Hemisphere and the eighth-intrinsically brightest known trans-Neptunian object. However, it was later found to be much dimmer, with an absolute magnitude (H) of 4.5. This value would make it a good dwarf planet candidate when using an albedo of 0.09, but it is probably much smaller than previously thought. It has been found to be a member of the Haumea family due to its Haumea-like orbit and the detection of water ice on its surface. This means 2009 YE7 could have an albedo of up to 0.7, resulting in a small size close to 200 kilometers. Its actual albedo is unknown.
Reader's Guide
2009 YE7 is significant as a classical Kuiper belt object and a member of the Haumea family, identified by its Haumea-like orbit and the detection of water ice on its surface. Its discovery at La Silla Observatory in Chile by David Rabinowitz added to the census of trans-Neptunian objects from the Southern Hemisphere. The object's history includes a notable revision in its absolute magnitude: initially thought to be 2.8, which would have made it the eighth-intrinsically brightest known TNO, it was later found to be much dimmer at 4.5. This revision underscores the challenges in estimating sizes and albedos of distant objects. As a Haumea-family member, it may have a high albedo up to 0.7, implying a size near 200 kilometers, but its actual albedo remains unknown, leaving its true size uncertain. With an absolute magnitude dimmer than H=1, it will not be automatically listed as a dwarf planet by the IAU. Its legacy lies in illustrating the dynamic nature of TNO classification and the importance of family associations in understanding the Kuiper belt's composition and history.
Did You Know?
- It has an absolute magnitude (H) of 4.5, dimmer than initially thought, and is a member of the Haumea family.
- Water ice has been detected on its surface, and its albedo could be as high as 0.7, implying a size close to 200 kilometers.
More in Trans-Neptunian Objects, Part 3 1-24
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